Fastener applying machine



Dec. 22, 1964 I H. G. ALLEN ETAL 3,162,097

FASTENER APPLYNG MACHINE Filed NOV. 9, 1962 4 Sheets-Sheet 1 De 22, 1964 H. G. ALLEN ETAL FASTENER APPLYING MACHINE 4 Sheets-Sheei 2 Filed NOV. 9, 1962 Ib-f fama Dec. 22, 1964 H. G. ALLEN ETAL FASTENER APPLYING MACHINE 4 Sheets-Sheet 3 Filed Nov. 9, 1962 Dec. 22, 1964 Filed NOV. 9, 1962 H. G. ALLEN ETAL FSTENER APPLYING MACHINE 4 Sheets-Sheet 4 INVENTOR.' dazzzZ/ezz 0120.7

TIMEX/S.

United States Patent Ollice n arcata? PatentedfDec. 22, 1964 3,l62,097 FASTENER APPLYENG MACE-HNE Howard G. Alien, Cranston, and Edward i. Fisher,

Westerly, R., assignors to Bostitch, inc., East Greenwich, Rl., a corporation of Rhode Island Filed Nev. 9, 1962, Ser. N 236,579 17 Claims. (Cl. 91-699) This invention relates to improvements in stapling machines and implements for driving staples or other types of fasteners into a workpiece to fasten it in place or secure its parts together. More particularly, the present improvements are adapted to be applied to a portable machine of the type shown and described in United States Letters Patent No. 3,055,344 dated September 25, 1962. The present invention also contemplates the provision of a safety device for the machine to prevent premature or accidental operation of the staple driving means until the machine has been placed on or struck against the workpiece on which it is to operate.

One object of the invention is to provide in a machine operated by pressure fluid, such as compressed air, an improved structure and method of operation of the reciprocable piston which actuates the staple driving means.

Another object is to provide improved valve `means for applying pressure to the piston to operate it in a driving stroke; and means to direct the pressure to the opposite side of said piston `for reversing its stroke to return it to inoperative position.

Another object is to simplify the means for operating the piston by providing a single valve for controlling the application of pressure to the piston both for driving it operatively and reversing its stroke.

An important object of the invention is to provide safety means for preventing premature or accidental operation of the staple driving means until the machine has been placed in Contact with or struck against the workpiece.

Another object is to provide a safety device which requires that both the contact means and the manually operable means must be actuated conjunctively before power is applied to the piston to drive it in an operative stroke.

Another object is to provide in a safety device workpiece contact means connected to the valve control means for preventing operation of the piston driving means un less the manually operable means has been actuated.

Another object is to provide valve control means actuated in stages, either lirst by said contact means and then by said manually operable means or in reverse order; rst by the manually operable means and eventually by the contact means.

Another object is to provide means in the safety device for maintaining the manually operable means inactive until said Contact means has made contact with the workpiece.

Further objects of the invention are to simplify and improve the valve structure for applying pressure to drive the piston in an operative stroke and for reversing the application of pressure to return the piston to its inoperative position. t

Another object is to provide an improved safety device for preventing the actuation of the staple driving means that may be applied to practically all types of portable machines without material alteration in the basic structure thereof.

While the present imporvements are herein shown and described as embodied in a machine of thertype disclosed in the patent referred to above, the novel and improved features thereof may be applied to machines of other construction and arrangement disclosed in the prior yart.

It is to be understood that the present disclosure is by way of example only, as regards the main elements of the machine, and different embodiments thereof may be used to advantage for practically all known types of portable fastener driving implements to assure the safe operation thereof; that is, to prevent accidental discharge of the staples or fasteners liable to cause injury to the individual operating the machine or to persons in the vicinity thereof.

The invention is herein shown as applied to use in a portable stapling machine of improved construction illustrated in the accompanying drawings and described in the following specification. In the drawings:

FIG. 1 is a side elevational view in reduced scale of a machine embodying the present invention;

FIG. 2 is la longitudinal sectional view in enlarged scale taken through the vertical axis of the machine showing the piston and its connected staple driver in inoperative position and the control valve operative to apply pressure to the under side of the piston for maintaining it suspended with the manually operable trigger inoperative;

FlG. 3 is a view similar to FIG. 2 showing the piston at the end of its driving stroke with the staple driver blade at the terminus of its descent after driving a staple into the workpiece and illustrating the manually operable trigger as having been moved into position to actuate the valve control means for exhausting pressure from under the piston;

FlG. 4 is a transverse sectional view through the main cylinder of the machine taken on line 4-4 of FlG. 2 and illustrating the control valve in top plan view;

FIG. 5 is a transverse sectional view through the main cylinder of the machine and the control valve taken on line 5 5 of FIG. 3;

FIG. 6 is a vertical sectional view of the control valve taken on line 6--6 of FIG. 4 and showing the parts of the control valve with their connections to the safety device which is illustrated as operative to prevent actnation of the staple driving means;

FIG. 7 is a similar sectional view, also taken on line 6 6 of FIG. 4 and showing the safety device with its manually operable means in position for actuating the valve means to control the operation of the staple driving piston; l

FIG. 8 is a view similar to FIG. 7, also taken on line 6-6 of FIG. 4, and showing the safety device with its contact means in position for actuating the valve means to control the operation of the staple driving piston;

tFIG. 9 is a view similar to FIGS. 6 and 7, also taken on line 6-6 of FIG. 4, and showing the safety device with both 'the manually operable means and the contact means shifted into position for 'actuating the control valve to cause the piston to be driven in an operative stroke; and

FIG. l0 is a part sectional view on line lll-10 of FIG. 4 with the pants of the control valve illustrated in the same position as in FIGS. 6 and 8 and showing therelation of lthe exhaust duct to the other passages in the valve casing.

Referring first to FIGS.` 1, 2 and 3 of the drawings, the mechanism of the present machine is housed in a casing 2 similar tov that of the machine illustrated in U.S. Patent No. 3,055,344 referred to aboveand comprising a vertical head 3 for-med on its interior with a cylinder 4 for receiving a reciproeable piston 5. Projecting rearwardly from the head 3 is a hollow handle 6, the interior of which forms a pressure fluid reservoir in communication with the open upper end ofthe cylinder 4 for maintaining constant pressure against the Vmain head of the piston 5. The upper portion of the head 3 of the casing 2 is constructed on its interior with an integral cylinder 7 of relatively small bore open at the top to the atmosphere.

The piston 5 is constructed with a main head 10 slidable 3 in the cylinder 4. An O-ring 11 held in a peripheral groove of the head acts to seal the head with the wall of the cylinder 4. The main piston head l@ has an extension rod 12 reaching up through the bore of the smaller cylinder 7 and formed on its upper end with an auxiliary head 1S. The piston head 15 is of usual construction, being formed with a peripheral groove in which is held an O-ring 15 acting to seal it with the interior wall of the cylinder 7. A at disk-shaped washer 18 located on top of the head 10 surrounding the extension rod 12 is adapted to seat against the lower end of the small cylinder 7 to limit the upward movement of the piston 5. As shown in FIGS. 2 and 3, the lower end of the cylinder 7 is formed with a radial slot or slots 19 t0 provide passageways for admitting pressure iiuid from the reservoir 8 into the bore of the cylinder 7 when the washer 18 on the head 1% is in contact with the end of the cylinder 7. The upper end of the cylinder d is formed with a small passageway 14 leading therefrom and opening into the reservoir for supplying pressure thereto when the piston head 1i? is at the upper end of its stroke as shown in FIG. 2.

It is to be particularly noted that a ditierential relationship exi-sts between the area on the upper side of the piston head l@ and the area on its under side. That is to say, the eiective area exposed to pressure labove the piston head 1) is restricted to its annular portion surrounding the cylinder 7; whereas the area on the under side of the piston head 10 is exposed across its full diameter corresponding to the bone of the cylinder 4. Due to this form of construction of the piston 5 full pressure within the cylinder 4 acts to normally maintain the piston raised against the constant pressure in the reservoir 8 as later explained.

A slot 17 or other suitable formation of the piston head 1S is provided for applying a screw-driver or wrench for turning the piston 5 which is connected by screw-threaded means to the staple driver blade 20. The purpose of this fior-m of construction is to provide for adjusting the connection between the piston 5 and driver blade 20 to regulate the efective length of the latter. The driver blade 2t) is connected to the piston 5 by an externally threaded plug Z1 screwed into an interiorly threaded cup-shaped annulus 22 on the under side of the piston head 10. The effective length of the driver blade below the piston 5 thus may be adjusted for driving staples to the required depth in the workpiece. The driver blade 20 is slidable through a slot 24 in a member 25 which may be constructed of resilient material to provide a bumper for cushioning the shock of the piston as it reaches the end of its downward stroke (FIG. 3 The lower end of the driver blade 20 is acc-ommodated in a slot lZ6 in the bottom Wall of the casing 2 which may be constructed as a cover 27 therefor and suitably fastened in place with a gasket `sealing the joint.

The lasteners as herein shown are in the form of U- shaped staples s adapted to be fed to the staple driver 2G as usually provided by supp-lying them in the form of a cartridge or stick slidably held within a magazine 3@ illustrated generally in FIGS. l, 2 and 3, but not specifically described herein since it forms no part of the present invention. A nosepiece 3S having a slotted throat or guideway for Yslidably supporting the driver blade 20 extends downwardly at the front end of the magazine 2. The

nosepiece 35 is of usual construction with an opening in nects the end of a hose or pipe 44 to' the valve 40 with its opposite end connected to a suitable source of supply of the pressure fluid. 'Ihe air or other pressure fluid supplied Vpiston 5 starts to descend.

through the hose 44 feeds into the interior of the valve casing 41 through a tapered opening 45 in a washer 46 yabutting the end of the litting 43. The opening 45 is tapered to adapt it to receive a ball closure 47 for closing it to prevent back pressure escaping therethrough. The opening 45' is preferably formed with one or more small grooves 4S to allow the air to slowly bleed therethrough when the hose 44 is disconnected from the machine.

The valve casing 41 is formed with a duct 50 leading from the end of the fitting 43 into a vertical bore 51 extending downwardly into a larger bore which forms a cylindrical chamber 52. Held in the chamber 52 is a cup-shaped member 53 arranged with its upper rim 54 forming a seat for the head of the puppet ft2. The poppet 42 has its stern 55 slidable in a bore 55 at the top of the bore 51. The head of the poppet 42 consists of a washer 57 of resilient material mounted on the lower end of the stem 55 and supported in place by a metal washer 58. Held in a peripheral groove in the head of the poppet 42 is an O-ring 59 constructed of resilient material and adapted to engage the wall of the bore 51 when the poppet is raised, as shown in FIGS. 3 and 9, to seal the bore against admission of pressure fluid from the duct 50.

At the side of the chamber 52 a port opens into an elbow-shaped duct 60 leading downwardly into an enlarged bore -31. Below the end of the enlarged bore 61 of the duct 6i) is a rectangular passageway 64 opening into the bottom of the main cylinder 4, see also dotted lines FIG. 5. A ball closure 62 normally resting on a pin 63 in the bore 61 is adapted to seat in the upper tapered end of said bore to form a check valve for sealing the end of the duct 6i) (FIG. 3).

Normally, the poppet 42 is held against the seat 54 to admit air through the duct 5t), chamber 51, bottom chamber 52 and elbow-shaped duct 60, and thence down into the passageway 64 to apply pressure to the under side of the piston 5 for maintaining it raised as shown in FIG. 2. Referring to FIGS. 4, 6, 7 and 8, a duct 70 leads from the lower chamber 52 into a chambered bore 71 at the side of the valve casing 41. The end of the chambered bore 71 is closed by a cover 72 formed at the center with a nozzle 73 in communication with the atmosphere. The nozzle 73 is normally closed by a exible diaphragm 74 in the chamber 71 under pressure from the duct 70.

Beneath the poppet valve structure described above is a cylindrical chamber (FIG. 2) containing a spoolshaped valve closure slidably mounted therein. The upper larger cylindrical head 86 of the member S5 is formed with a peripheral groove containing an O-ring 87 for sealing it to the interior wall of said chamber 80. Joined to the head 86 by a stern 8b' is a lower head 89 grooved peripherally to contain an annular gasket 9G adapted to seat against the upper rim of the exhaust opening 91 in the bottom plate or cover 27 of the main casing 2 of the machine (FIG. 2). The opening 91 is for venting pressure from the cylinder 4 into the atmosphere as the piston 5 descends therein (FlG. 3). Pressure acting against the under side of the larger head 86 of the closure 85 acts to raise it and open the exhaust vent 91 as the Normally, the spool-like closure 85 is depressed to close the exhaust opening 91 by the air admitted into the chamber Sil through the duct 95 (FlGS. 9 and 10). The several parts of the control valve 4d described above are shown in FIGS. l and 2 intheir normal relationship when the machine is prepared for operation.

The present improved safety device comprises a contact member or element 199, herein illustrated as constructed of wire and mounted to slide vertically in a slot 101 in the side of the valve casing 41 (FIGS. 1 and 5) with its lower end positioned to strike against a workpiece W (FIG. 3). The lower upright portion of the contact member 15H1 is slidably held in a perforated bearing lug 162 on the 'side of the magazine 3@ to adapt it to project below the bottom of the casing 2 adjacent the nosepiece 35. The

wire of the member 100 is bent to form an angular portion 1113 and bent again into a vertical length 104 extending upwardly. The upper end of the member 100 is formed into a hook S inserted through a hole in the end of a pivoted rocker arm 110. The rocker arm 110 is pivoted at its center on the right-angular bent upper end of a wire link 111 slidable in a slot 112 in the side of the head 3. The lower end of the link 111 Iis bent at right-angles at 113 and inserted through a hole in the upper end of the stem 55 of the poppet 42 (FIGS. 2, 4, 6-9). This form of construction provides means for raising the poppet 42 in the valve 4i) in the manner and for the purpose later explained. To actuate the poppet 42 it is necessary that the rocker arm 11d be lifted bodily through the cooperation of both the contact element 10d and a manually operable trigger 115.

The trigger 115 is pivoted at 116 in a slot between flanges 117 projecting downwardly from the under side of the handle 6. To provide for this cooperation between the elements the trigger 115 has a lug 118 at its forward end normally clearing, but adapted to engage under, the edge of the rocker arm 110 (FIG. 3) when the contact element 100 has been slid upwardly by the engagement of its lower end with the workpiece W as shown in FIG. 3. At this juncture, the rocker arm 110 will have assumed the relationship shown in FIG. 8 with the lug 118 on the trigger 115 positioned under its right-hand end so that when the trigger is pressed upward it will raise the rocker arm 110 bodily (FIG. 9). Consequently, the poppet 42 will be lifted off its seat 54 to actuate the control valve 40 for exhausting pressure from beneath the piston 5 to cause it to be driven by pressure thereabove.

Method of Operation The method of operation of the complete apparatus is explained as follows: With the fastener applying machine prepared for operation by connecting it to a source of pressure fluid such as compressed air, supplied through the hose 44 and nipple 43 to the control valve 4t, air entering the valve 40 will force the ball closure 47 away from the opening in the collar 46. Air will feed through the duct 50 into the upper bore 51 of the valve 40 to apply pressure to the poppet 42 for maintaining its head 57 closed against the seat 54. Consequently, air will feed past the poppet 42 to iiow through the port in the elbow-shaped duct 60 and down therethrough as the ball 62 rests on the pin 63, thus opening said duct into the lower passage 64. At this time the air admitted into chamber 71 feeds through duct 76 to act against the flexible diaphragm 74 (FIG. 6) for closing it against the opening in the exhaust nozzle 73. Also at this juncture, air admitted into the chamber 71 of the valve 4t) feeds through the duct 95 (FIG. lO) to enter the upper end of the bore Si) and act against the head 86 of the spool-shaped closure 85 for closing its head 59 against the relatively large exhaust opening 91. With the parts of valve 40 in the relationship shown in FIG. 2, air issuing through the elbowshaped duct 60 flows past the ball 62 resting on pin 63 to enter the bottom of the main cylinder 4 and apply pressure to the under side of the piston head 1t) for raising the piston 5 and sustaining it in inoperative relationship engaging against the end of the smaller cylinder 7. With the piston 5 at the upper end of the cylinder l the O-ring 11 surrounding its head 10 is located above the passage 14 which is therefore open to admit pressure into the interior of the reservoir S and the cavity surrounding the smaller cylinder 7. Constant pressure is thus applied against the upper side of piston head 1t) at all times during operation of the machine. ConstantI pressure also feeds through the passages 19 into the bore of the cylinder 7 to act against the auxiliary piston and assist in sustaining the main piston 5 raised. In this way constant kpressure is supplied to the reservoir 8 to prepare the machine for its initial operation and likewise to replenish the supply of air in the reservoir S after each operative stroke of the piston 5.

It has been explained that the piston head 10 has a differential relationship of the areas on its upper and lower sides. That is, the area on the upper side of the piston is restricted to the annular space surrounding the cylinder 7; whereas, the full expanse of the area on its under side is exposed to pressure in the cylinder 4. Due to this differential relationship of the effective exposed areas on opposite sides of the piston head 10 the piston 5 will normally be held sustained in inoperative relationship at the upper end of the cylinder 4 with the driver blade 20 retracted for feeding a staple beneath its lower end. When, however, the pressure in the cylinder 4 is vented its thrust on the piston 5 is released to cause it to be driven downwardly for actuating the driver blade 20 to drive a staple into the workpiece W as shown in FIG. 3. The air in the cylinder 4 is exhausted from under the piston head 10 by operation of the spool-shaped valve closure to open the orifice 91; it being understood that the contact element 11M) and the trigger 115 must be actuated concordantly before the piston is driven.

FIGS. 6 to 9, inclusive, show the sequence of operations in the poppet 42 and the valve closure 85 in connection with the means actuated by the elements of the safety device. When the machine is placed lagainst the workpiece W the end of the Contact element is engaged therewith to slide it upwardly, causing its upper connection with one end of the rocker arm to rock the latter into the position shown in FIG. 8. The opposite end of the rocker arm 110 will therefore be swung downwardly into position to be engaged by the lug 118 on the trigger 115. This action has no effect to lift the poppet 42 off its seat 54 in the chamber 52 since the trigger 115 is normally inclined downwardly as illustrated in FIG. 2. Thus, when the machine is placed against the workpiece W and the parts are in the relationship last described the driver blade 2t? remains inoperative until the trigger 115 is actuated. The operator usually maintains the machine in position for applying staples or other fasteners at the desired location by grasping the handle 6 with the fingers relaxed under the trigger 115. Then by compressing the fingers against the trigger and raising it into the position shown in FIG. 3 the lug 11S on the forward end of the trigger will engage under the rearward end of the rocker arm 110 (FIGS. 3 and 9) and raise the arm as the support at its opposite end by the contact element acts as the fulcrum. As the arm 110 is swung upwardly its connection by the link 111 to the poppet 42 will lift the latter as shown in FIG. 9. p

As the poppet 42 is lifted away from its seat 54 (FIGS. 3 and 9), its O-ring 59 closes the lower end of the bore 51 to prevent the air from entering the chamber 52 and feeding through duct 5d. At this point in the operation of the valve 44B air in the chamber 71 is released through duct 7 0 and exhausted out through duct 75 to the atmosphere. When the aforesaid action takes piace air pressure in the chamber Sti above the closure 85 will ow through the duct 95 (FIG. l0) and into chamber 71 to displace the diaphragm 74 (FIG. 9) and open the nozzle for exhausting the air into the atmosphere, see also FIG. 5. Thus pressure above the valve closure 85 is exhausted. There- Vupori pressure from the cylinder 4 flowing through the pasblade 2t) carried by the piston is thereby actuated to drive a staple down in the nose 35 to insert it in the workpiece. As air in the cylinder 4 is exhausted rapidly through the relatively large port or opening 91, the constant pressure in the reservoir 8 acts to drive the piston 5 and driver blade 251 down with maximum force for setting the staple in the workpiece.

Return of iiistonv Upon completion of the driving stroke the piston is returned to its initial position at the top of the cylinder 4 and the driver Z6 withdrawn from the throat in the nosepiece 35, thereby permitting a staple to be fed thereinto -in preparation for the next driving operation. This takes place upon raising the implement from the workpiece W to release the contact element 160 and cause it to drop; or in other instances by releasing the trigger 115 to cause it to disengage the rocker arm 1li?. Reiease of the rocker arm 119 by either the contact element 100 or the trigger 115 permits the pressure from the duct 50 entering the bore 5l to force the poppet 42 downward, thereby engaging the head 57 thereof with the seat 54 and thus closing the exhaust duct 75 leading to the atmosphere. Pressure uid from the bore Si is permitted to pass through the bore '70 to force the diaphragm 7d in the chamber 71 against the nozzle 73 thereby closing this exhaust orifice. The pressure iiuid then ilows through the duct 9S to the chamber S0 above the closure member 85 to force it downward for closing the enlarged opening 91 by the head 89. Pressure admitted through the duct 50 to the bore 51 is permitted to pass through the elbow duct 69 to force the ball 62 downward against the crosspin 63, thus permitting pressure to be admitted through the passageway 64 and into the bore of the cylinder 4 beneath the head of the piston 5. Since the effective pressure area on the under side of the piston 5 is greater than the eifective pressure area on Vits upper side, the piston 5 is forced upwardly against the accumulated pressure in the reservoir S above the piston 5 (FIG. 2). Since the head 10 of the piston 5 when raised to its uppermost position against the end of the cylinder 7 is disposed above the passageway i4, air from the cylinder 4 beneath the piston is permitted to pass therethrough into the reservoir 8 to compensate for any dissipation of the pressure therein. The machine is now prepared for further staple driving operations.

The present invention is illustrated and described herein as embodied in a machine resting upon a horizontal workpiece with the driver blade arranged for vertical reciprocation. It is to be understood, however, that the machine is adapted for operation in other positions to perform diierent kinds of work. For example, it may be used in the manner of a hammer for nailing sheathing and wall board to vertical wall structures and for fastening diierent types of roofing to the sloping surfaces of roofs. Also it may be manipulated in a relationship opposite to that shown in the drawings for tacking or nailing sheathing to ceilings. In such instances where the machine is wielded in the manner of a hammer the operator grasps the handle 6 and applies pressure to the trigger 115 with his fingers (FIG. 7). The head of the machine is then struck against the workpiece to cause the contact element 190 to be shifted into position for cooperation with the trigger 115 to dispiace the poppet 42 in the valve 40 and apply power to the piston 5 for reciprocating the driver blade 20 and driving a fastener into the work piece. In other words, the safety device prevents application of power to the driving means until the machine is actually struck against or otherwise contacted with the workpiece. Accidental discharge of the staples or fasteners of other type is thus prevented at all times and the danger of injury to the operator or other persons within range is eliminated. i

When Work with the machine has been finished and it is to be transported to a diiferent locality for other work, it is advisable to disconnect the air supply hose 44 to render it inoperative. Depressurization of the implernent is accomplished by the gradual escape of air or other pressure fluid through the washer opening 45. Upon removal ofthe hose 44 the air accumulated in the reservoir 8 and other chambers of the casing 2 will act against the ball 47 to close the opening 45 in the washer 46. The air will then escape slowly through the slots 4S in the opening 45 to discharge into the atmosphere. Thus, all the air in the reservoir 8 rand the cavity above the cylinder d will be exhausted to deactivate the piston 5 and driver blade 2d connected thereto. This makes for further safety during handling and transporting the implement by preventing accidental discharge of the fasteners therefrom.

While the present improvements are described and illustrated as embodied in a machine of preferred form of construction, the structure and arrangement of its elements may be modified without departing from the spirit or scope of the invention as expressed in the accompanying claims. Therefore, without limitation in this respect, we claim:

l. ln a machine for driving fasteners, a cylinder, a piston siidable in said cylinder, a driver reciprocable by said piston for driving the fasteners into a workpiece, a valve connected to a source of pressure fluid, means in said valve for energizing the pressure duid in said reservoir to drive said piston in an operative stroke, a manually operable trigger, and safety means for preventing accidental driving of said piston, said safety means including a contact element movable by engagement with the workpiece, and an intermediate member movable by concomitant action of said trigger and said contact element, said intermediate member being connected to operate said valve for reciprocating said piston to drive fasteners into the workpiece.

2. In a machine for driving fasteners, a cylinder, a piston slidable in said cylinder, la driver reciprocable by said piston, a reservoir for pressure fluid, a valve directly connected to a source of pressure fluid, means in said valve for feeding pressure fluid to said cylinder and reservoir, a manually operable trigger, and safety means including a contact element actuated by engagement with the workpiece, la movable member intermediate said trigger and said Contact element, and means connecting said intermediate movable member to said valve, said intermediate member being movable by concomitant action of said trigger and said contact element to actuate said means in said valve for energizing the pressure fluid in said reservoir to reciprocate said piston and driver to drive a fastener into the workpiece.

3. In a fastener driving machine, a cylinder, a piston slidable in said cylinder, a driver reciprocable by said piston, a reservoir for pressure duid, a valve for supplying pressure fluid to said cylinder and said reservoir, a closure in said valve shiftable to control the action of the pressure fluid on said piston, a rockable member connected to said valve closure for shifting it, a contact element movable by engagement with a workpiece, said contact element adapted to move said rockable member to a limited extent, and a manually operable trigger adapted to cooperate with said contact element to displace said rockable member to the required extent for shifting said valve closure to exhaust pressure iluid from said cylinder whereby the pressure iluid in said reservoir is energized to reciprocate said piston for driving a fastener into the workpiece.

4. in a machine for driving fasteners, a cylinder, a piston slidable in said cylinder, a driver reciprocable by said piston for driving fasteners into a workpiece, a reservoir for pressure iluid in communication with said cylinder, a valve connected to a source of pressure huid, control means in said valve operative to energize the pressure fluid in said reservoir to drive said piston in an operative stroke, a manually operable trigger, safety means for preventing premature operation of said piston including a contact element movable by engagement with the workpiece, an intermediate member movable to a limited extent by said Contact element and connected to said valve control means, said trigger adapted to cooperate with said contact element to displace said intermediate member bodily to thereby shift said valve control means for energizing the pressure fluid in said reservoir to drive said lpiston in an operative stroke.

5. In a machine of the type indicated, a cylinder, a piston slidable in said cylinder, means reciprocable by said piston, contact means movable by engagement with a workpiece to be operated upon by said machine, a valve having means for controlling the action of said pressure duid, a member movable by said contact means andconnected to actuate said control valve for causing the pressure duid to drive saidpiston, and a manually operable trigger engageable with said last-named movable member for cooperation with said contact means to actuate said valve for energizing the pressure duid in the reservoir to drive said piston in an operative stroke.

6. In a piston driven machine, a cylinder, a piston slidable in said cylinder, a valve for applying duid pressure to one side of said piston and exhausting pressure from its opposite side to cause said piston to be reciprocated, means in said valve for controlling the application of pressure to and exhaustion of pressure from said piston, a contact element for engagement with a workpiece to be operated upon, a manually operable trigger, and a member movable by concomitant action of said contact element land said trigger, said member being connected to actuate said control means in said valve to eifect reciprocation of said piston.

7. In a piston driven machine, a cylinder, a piston reciprocable in said cylinder, a valve for supplying pressure duid to reciprocate said piston in said cylinder, control means in said valve for exhausting pressure duid from one side of said piston to cause expansion of the pressure duid on its opposite side to drive said piston, a movable member for actuating said valve control means, a contact element movable by engagement with a workpiece for moving said movable member, manually operable means for moving said movable member, said contact element and manually operable means being adapted to act concomitantly to move said last-named movable member for actuating said valve control means.

8. In a machine of the type indicated, a cylinder, a piston slidable in said cylinder, a Valve connected to a source of pressure fluid, a poppet in said valve movable to exhaust pressure duid from one side of said piston to cause the pressure duid on its opposite side to drive said piston` in an operative stroke, a link connected at one end to said poppet for shifting it, a rocker arm pivotally connected to the opposite end of said link, a contact element movable by engagement With a workpiece, said contact element connected to one end of said rocker arm, and a manually operable trigger movable to engage with the opposite end of said rocker arrn for cooperation With said contact element to lift said arm bodily and shift said poppet for actuating the control means in said valve.

9. ln a pressure duid operated motor, a valve for controlling said pressure duid to edect actuation of said motor, a contact element for engagement with a Workpiece to be operated upon, a manually operable trigger, and safety means for preventing premature operation of said motor, said safety means comprising a member movable to actuate said control valve, said movable member being moved to actuate said control valve by concomitant action of said contact element and said trigger.

l0. In a pressure duid operated motor for driving a machine, a valve for controlling the pressure duid to operate said motor, contact means movable by engagement with a workpiece to be operated upon, a manually operable trigger, and safety means comprising a member movable to actuate said control valve, said movable member being shiftable to the required extent to actuate said conmovable to a limited extent by said manually operable means and movable to a further extent by said contact means to actuate said valve control means for causing the pressure duid to operate said motor.

l2. A duid pressure motor comprising a cylinder completely open across its upper end, a reservoir of relatively large capacity for containing pressure duid in direct communication With said cylinder through its open end, a differential piston slidable in said cylinder and constructed with its upper side opposed to pressure in said reservoir of less eifective area than the effective area on its under side opposed to pressure in said cylinder, a manually operable control valve connected to a source of pressure duid, means connecting said control valve to supply full pressure to said cylinder and said reservoir, an exhaust valve operative by pressure from said control valve to vent pressure duid from said cylinder on the under side of said piston and cause pressure from the reservoir on its upper side to drive said piston in an operative stroke, and means operative by said control valve for applying pressure to close said exhaust valve and cause pressure duid to feed into said cylinder to exert its force on the under side of said piston for returning it to inoperative position after each operative stroke thereof.

13. A duid pressure motor comprising a cylinder having an open end, a reservoir for duid pressure in communication with said Vcylinder through its open end, means to supply pressure duid to said cylinder and said reservoir, a piston slidable in said cylinder and constructed with a greater eifective area on its side opposed to pressure in said cylinder than the effective area on its opposite side opposed to pressure in said reservoir, a control valve connected to supply pressure duid to the end of said cylinder opposite from its end in communication with said reservoir, an auxiliary exhaust valve connected to the last-mentioned end of said cylinder and having a vent for exhausting pressure duid from said cylinder, closure means in said exhaust valve operative by pressure from said control valve for normally maintaining said vent in said exhaust valve closed, means in said control valve for exhausting pressure from said trol valve only by concomitant operation of both said closure means in said exhaust valve to cause opening of the vent therein, and means connecting said cylinder with said auxiliary Valve to cause exhaust of pressure duid -from the cylinder through said vent for thereby energizing pressure. in said reservoir to drive said piston in an operative stroke.

14. A pressure duid motor comprising a casing having a cylinder therein completely open across its upper end, a reservoir of relatively large capacity for containing pressure duid, said reservoir arranged in direct communication With said cylinder through its open end to supply full pressure thereto, a dilferential piston slidable in said cylinder and constructed with its side opposed to pressure in the reservoir of less effective area than the eifective area on its opposite side exposed to pressure in said cylinder, a manually operable control valve connected to a source of pressure duid, said control valve connected to said cylinder and said reservoir to supply pressure duid thereto, an auxiliary exhaust valve having exhaust passages including a vent to the atmosv phere for releasing pressurefrom the end of said cylinder opposite its end connected'to said reservoir, means connecting said control valve to said exhaust valve to apply pressure thereto for normally maintaining its vent closed, and means for operating said control valve to release pressure in said exhaust valve and cause its vent' to be opened by pressure from said cylinder for thereby releasing pressure on the side of said piston of largest eifective area to energize the pressure in said reservoir on its opposite side to drive said piston in an operative stroke.

15. In a device of the type specified, a casingvhaving a cylinder therein with a relatively large intake opening at one end, a reservoir for pressure duid in direct communication with said cylinder through its intake opening, a differential piston reciprocable in'said cylinder and constructed with ythe eiective area on `its side opposed to pressure in said cylinder greater than the effeet-ive area on its opposite side opposed to pressure in said reservoir, a manually operable control valve, means 4connecting said vcontrol Valve to a source of pressure fluid, means connecting said control valve to supply pressure iluid to said cylinder and said reservoir, an exhaust valve connected to said cylinder and having an opening to the atmosphere for venting pressure from the side of said piston having the greatest elective area, 'a closure inV said exhaust valve arranged to seat across its Vent opening, and means connecting said control valve to apply pressure to said closure to normally maintain its vent opening closed, said control valve having .exhaust means to release pressure from the closure in said exhaust valve whereby the pressure in said cylinder normally maintaining said piston inoperative is exhausted and pressure in said reservoir energized to drive said piston in an operative stroke.

16. An apparatus as defined in claim 15 wherein said casing is provided with an auxiliary cylinder of less diameter than `the main cylinder disposed in axial aline' ment with said main cylinder, said smaller cylinder open to theatmosphere at one end, and a supplemental piston connected to said main piston to slidejin said auxiliary cylinder during reciprocation of said main piston.

17. A fluid pressure motor comprising a cylinder, a

piston slidable in said cylinder, means for supplying pressure to said cylinder for reciprocating the piston in said cylinder, manually operable valve means for controlling the application of pressure to said piston, a smaller cylinder extending from said main cylinder in axial alinement therewith and open to the atmosphere at its outer end, a smaller piston carried by an extension of said main piston to slide in said smaller cylinder, a driver element connected to said Vmain piston by screwthreaded means, means for preventing rotation of said driver element with respect to said piston, and means on said smaller piston engageable through the open end of said small cylinder for rotating the main piston in said cylinder to adjust the screw-threaded connecting means of the driver element whereby to regulate its extent of projection from said main piston.

References Cited by the Examiner UNITED STATES PATENTS 2,546,114 3/51 Triplet-t et al. 91-442 X 2,802,451 8/57 Chellis et al. 91-399 2,826,176 11/58 Chellis et al. 91-399 2,854,953 10/58 Osborne 173-2 2,932,030 4/60 Lang 173-2 2,989,948 6/61 Forrester 91-420 X FRED E. ENYGELTHALER, Primary Examiner.

SAMUEL LEVINE, Examiner. 

1. IN A MACHINE FOR DRIVING FASTENERS, A CYLINDER, A PISTON SLIDABLE IN SAID CYLINDER, A DRIVER RECIPROCABLE BY SAID PISTON FOR DRIVING THE FASTENERS INTO A WORKPIECE, A VALVE CONNECTED TO A SOURCE OF PRESSURE FLUID, MEANS IN SAID VALVE FOR ENERGIZING THE PRESSURE FLUID IN SAID RESERVOIR TO DRIVE SAID PISTON IN AN OPERATIVE STROKE, A MANUALLY OPERABLE TRIGGER, AND SAFETY MEANS FOR PREVENTING ACCIDENTAL DRIVING OF SAID PISTON, SAID SAFETY MEANS INCLUDING A CONTACT ELEMENT MOVABLE BY ENGAGEMENT WITH THE WORKPIECE, AND AN INTERMEDIATE MEMBER MOVABLE BY CONCOMITANT ACTION OF SAID TRIGGER AND SAID CONTACT ELEMENT, SAID INTERMEDIATE MEMBER BEING CONNECTED TO OPERATE SAID VALVE FOR RECIPROCATING SAID PISTON TO DRIVE FASTENERS INTO THE WORKPIECE. 